Problems with Theme Variables

On my local computer, my theme works just fine. However I tried to host it, all the variables that I have used in my theme such as $base_path, $directory etc are not working. What shall I do? Could it be, file access problems?

I see a lot of people have this particular problem, and I had similar problems on my Ubuntu machine because of file permissions, since it was on my local machine I gave it full permission for everyone and it worked. So what do you think, is the real problem?